抗原变异可使得多种致病微生物易于逃避宿主免疫应答。表达在感染红细胞表面的恶性疟原虫红细胞表面蛋白1（PfPMP1）与感染红细胞、内皮细胞、树突状细胞以及胎盘的单个或多个受体作用，在黏附及免疫逃避中起关键的作用。每个单倍体基因组var基因家族编码约60种成员，通过启动转录不同的var基因变异体为抗原变异提供了分子基础。

疟原虫var基因转换速率变化导致抗原变异[英]／Paul H, Robert P, Christodoulou Z, et al//Proc Natl Acad Sci U S A

Statistical method for testing the neutral mutation hypothesis by DNA polymorphism.

So far in this course we have dealt entirely with the evolution of characters that are controlled by simple Mendelian inheritance at a single locus. There are notes on the course website about gametic disequilibrium and how allele frequencies change at two loci simultaneously, but we didn’t discuss them. In every example we’ve considered we’ve imagined that we could understand something about evolution by examining the evolution of a single gene. That’s the domain of classical population genetics. For the next few weeks we’re going to be exploring a field that’s actually older than classical population genetics, although the approach we’ll be taking to it involves the use of population genetic machinery. If you know a little about the history of evolutionary biology, you may know that after the rediscovery of Mendel’s work in 1900 there was a heated debate between the “biometricians” (e.g., Galton and Pearson) and the “Mendelians” (e.g., de Vries, Correns, Bateson, and Morgan). Biometricians asserted that the really important variation in evolution didn’t follow Mendelian rules. Height, weight, skin color, and similar traits seemed to

Human biochemical genetics

Genetics and analysis of quantitative traits

Gene families are growing rapidly, but standard methods for inferring phylogenies do not scale to alignments with over 10,000 sequences. We present FastTree, a method for constructing large phylogenies and for estimating their reliability. Instead of storing a distance matrix, FastTree stores sequence profiles of internal nodes in the tree. FastTree uses these profiles to implement neighbor-joining and uses heuristics to quickly identify candidate joins. FastTree then uses nearest-neighbor interchanges to reduce the length of the tree. For an alignment with N sequences, L sites, and a different characters, a distance matrix requires O(N^2) space and O(N^2 L) time, but FastTree requires just O( NLa + N sqrt(N) ) memory and O( N sqrt(N) log(N) L a ) time. To estimate the tree's reliability, FastTree uses local bootstrapping, which gives another 100-fold speedup over a distance matrix. For example, FastTree computed a tree and support values for 158,022 distinct 16S ribosomal RNAs in 17 hours and 2.4 gigabytes of memory. Just computing pairwise Jukes-Cantor distances and storing them, without inferring a tree or bootstrapping, would require 17 hours and 50 gigabytes of memory. In simulations, FastTree was slightly more accurate than neighbor joining, BIONJ, or FastME; on genuine alignments, FastTree's topologies had higher likelihoods. FastTree is available at http://microbesonline.org/fasttree.

/pdf/fast-tree-computing-large-minimum-evolution-trees-with-4grq0gwfpy.pdf

Fast Tree: Computing Large Minimum-Evolution Trees with Profiles instead of a Distance Matrix

We have tested the response of the Drosophila parasitoid Leptopilina clavipes to synthetic (z)-11octadecenyl acetate (cVA), a major component of the aggregation pheromone of various Drosophila species, including D. phalerata, which is L. clavipes main host. We found that L. clavipes is attracted towards patches treated with synthetic cVA.

The response of Leptopilina clavipes (Hymenoptera: Figitidae) to cVA, a major component of Drosophila aggregation pheromone

Using biological invasions to improve plant defense theory – S. B. Endriss, C. Alba & R. A. Hufbauer (https://doi.org/10.1111/eea.13195).

Editor's Choice: August 2022

Fall armyworm, Spodoptera frugiperda (J.E. Smith) (Lepidoptera: Noctuidae), is a voracious pest of various crops, such as maize, rice, and sugarcane. Originally from the tropical and subtropical regions of the Americas, it recently spread around the world. As populations can be resistant to pesticides, integrated pest management (IPM) is important, relying on a combination of chemical, physical, and biological control. This special issue of Entomologia Experimentalis et Applicata includes both fundamental and applied studies on fall armyworm biology, monitoring, and control, setting the stage for the development of effective, sustainable strategies to protect crops against fall armyworm, both in its native range and in areas where it has invaded.

Biology of fall armyworm – an introduction

During the transition from sexual to asexual reproduction, a suite of reproduction-related sexual traits become superfluous, and may be selected against if costly. Female functional virginity refers to asexual females resisting to mate or not fertilizing eggs after mating. These traits appear to be among the first that evolve during the gradual transition from sexual to asexual reproduction. The genetic basis of female functional virginity remains elusive. Previously, we reported that female functional virginity segregates as a single recessive locus in the asexual parasitoid wasp Asobara japonica. Here, we investigate the genetic basis of this trait by quantitative trait loci (QTL) mapping and candidate gene analyses. Consistent with the segregation of phenotypes, a single QTL of large effect was found spanning over 4.23 Mb and comprising at least 131 protein-coding genes, of which 15 featured sex-biased expression in the related sexual Asobara tabida. We speculate that two of these 15 genes may be of particular interest: CD151 antigen and nuclear pore complex protein Nup50. Overall, our results are consistent with a single gene or a cluster of linked genes underlying rapid evolution of female functional virginity in the transition to asexuality. Once a mutation for rejection to mate has swept through a population, the region comprising the gene(s) does not get smaller due to lack of recombination in asexuals.

/pdf/a-single-qtl-with-large-effect-is-associated-with-female-bklsqx6ux5.pdf

A single QTL with large effect is associated with female functional virginity in an asexual parasitoid wasp

Revisiting the hymenopteran diploid male vortex: a review of avoidance mechanisms and incidence – K. Leung & H. van der Meulen (https://doi.org/10.1111/eea.13234) Revisiting the hymenopteran diploid male vortex: a review of avoidance mechanisms and incidence – K. Leung & H. van der Meulen (https://doi.org/10.1111/eea.13234). Insect populations are declining at an alarming rate. Hymenopterans (ants, bees, wasps, and sawflies) have long been considered to be at particular risk of extinction due to loss of genetic variation. Many species have a sex determination system that is vulnerable to inbreeding, causing sterile diploid males and a reduction in allelic diversity, leading to even more sterile males, until the population dies out: the ‘diploid male vortex’. Leung and van der Meulen critically analyse the literature for support of this long-held view. They identify multiple ways of how social and non-social hymenopterans avoid inbreeding and conclude that the diploid male vortex may only act under very specific conditions. Their study addresses the role of genetic deterioration in the insect biodiversity crisis and has important implications for hymenopteran breeding and conservation. 

https://onlinelibrary.wiley.com/doi/pdfdirect/10.1111/eea.13240

Leo W. Beukeboom

Papers

The response of Leptopilina clavipes (Hymenoptera: Figitidae) to cVA, a major component of Drosophila aggregation pheromone

Editor's Choice: August 2022

Biology of fall armyworm – an introduction

A single QTL with large effect is associated with female functional virginity in an asexual parasitoid wasp

Editor's Choice: December 2022